TECHNICAL FEATURE:

Adaptive Cruise Control

by David Finlay (27 November 2002)

Every car manufacturer in the world has had to rethink its views on safety over the last few decades. Safety became a hot topic in the 1960s, when American campaigner Ralph Nader pointed out that the Chevrolet Corvair was apt to fall over if you drove it through a slalom at town speeds, and that this really wasn't good enough. Nader became something of a hate figure in the industry at the time, but since then safety has become one of the key selling points for new cars, as the advertising potential of getting a good score in the Euro NCAP tests demonstrates.

Nowadays cars are generally much more convenient things in which to have an accident than they used to be. The chances of being killed or injured in a minor bump have been greatly reduced. But this is passive safety - the tendency for a car to protect its occupants during an accident.

Much less attention has been paid to active safety - the ability of the car to prevent an accident from happening in the first place. At the moment this is almost entirely the responsibility of the driver, and we all know the possible results of even a moment's lack of concentration while driving.

But active safety is one of the possible advantages - traffic management, as we'll see, is another - derived from the Adaptive Cruise Control (ACC) systems which are gradually being offered as standard or optional equipment on an increasing number of road cars. And the key technology for it is supplied by a UK company. E2V Technologies has operations in the US, Canada, France and Germany, but it's based here, and what it does is create systems for the automotive, defence and space industries, among others.

Normal cruise control allows you to set your intended speed and leave the system to make sure the car keeps to it. In order to change speed, you have to disable or reset the system. It may make for more relaxed motorway driving, but it's not in itself much of an aid to safety.

ACC is much more pro-active. The system reads the road ahead and makes the car slow down if, say, you are closing up on the car in front. It is already standard equipment on the BMW 7-Series, the Jaguar XJ range and the Audi A8, but like other developments such as traction control, ABS, satellite navigation and so on, ever-reducing costs mean that ACC will start percolating down to cheaper models. In fact, ACC is to be fitted as standard to the Fiat Stilo Abarth, so you can see that the process has already started.

E2V's patented Gunn Diode technology, already used in fighter aircraft, is behind all this. It operates at 77GHz (that's 77 million pieces of information per second), and crucially it's based on microwaves. You can get much the same effect with lasers, but lasers can't be relied on to provide accurate distance information in rain or fog. Microwaves are not affected by visibility, so weather conditions are not an issue.

Despite the introduction of the system to the market place, these are still early days. The current system can measure up to 150m ahead of the car and reduce the car's speed if an obstruction appears. What it can't do, at the moment, is bring the car to a halt, but E2V reckons that by 2004 it will have a system which will not only do this but also bring the car back up to its set cruising speed without any driver input at all.

Two years further on, E2V expects that ACC will be able to offer pedestrian avoidance based on six short-range transmitters positioned around the vehicle, and also a lane control system to ensure that the car does not veer off-line.

So far we've only considered systems fitted to the car itself. But there's another possibility. Imagine two cars driving along a road. The one in front encounters a sudden change for the worse in road conditions, and automatically slows down (perhaps switching on its lights and wipers at the same time).

The second car hasn't encountered these conditions yet, but it's just about to. The first car alerts a roadside communication system to the new situation, and this signal is then passed on to the second car, which also slows down and does whatever else appears to be necessary.

The difficult bit here, of course, is the roadside communication system. Assuming the necessary infrastructure is put in place, E2V reckons that the rest of it could all be up and running by 2010.

Although active safety is not specifically what ACC is designed for, there are clearly enormous potential benefits. One of most significant points is that rear-end collisions could be cut down substantially, since ACC can monitor the situation 77 million times while you're looking in your rear-view mirror. And the potential of a rear-end crash happening in the first place is greatly reduced if the car won't allow itself to get too close to the one in front.

Of course, there is a political issue to be considered here. It's easy to imagine that in ten years' time we'll all be driving around practically hands-free, in the control of some computerised Big Brother which dictates where we can and can't drive, and charges us for each journey. Personally, I don't want to end up in a situation where I can no longer gain any enjoyment from driving, and I suspect that many CARkeys readers will feel the same.

On the other hand, who enjoys commuting to and from major cities? That's an example of driving being used as a means to an end, and far too many people are killed or injured each year while that end is being achieved, either by themselves or by whoever is behind the wheel of the vehicle that is about to run them over. In this case, driving enjoyment doesn't come into it - safety is the major issue. You can't stop progress; the important thing is to use it wisely.

Whatever happens, the ACC market looks set to explode. E2V's projected figures make startling reading. In 2002 there are no more than 100,000 vehicles fitted with ACC, but that figure is set to reach eight million in four years' time, with Europe, South-East Asia and the US accounting for about a third each. Around 17% of all European-built cars are likely to have ACC fitted as standard by then.

Expansion is bound to slow down thereafter, but by 2010 E2V reckons that the global market will be 11.5 million units, representing an industry value of around $2.4 billion - and enormously more than that saved in repair bills, hospital bills and, indeed, funeral bills.

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